1. Field of the Invention
The present invention relates to an optical apparatus.
2. Description of the Related Art
In the field of an optical apparatus such as a projector or a microscope, a structure for attaching a lens barrel to an optical apparatus body (hereinafter referred to as “apparatus body”) by means of plate claws is known. An example of such a structure is disclosed in Japanese Unexamined Patent Application Publication No. H4-307528. In the structure of an optical apparatus disclosed in Japanese Unexamined Patent Application Publication Number H4-307528, three plate claws (outer circumferential convex parts) are formed at an apparatus-body-attachment part of a lens barrel. On the other hand, a single thread groove and cutout regions through which the plate claws can be inserted into the groove are formed in the apparatus body. A concave part is formed in the outside of each plate claw. In addition, inner circumferential convex parts are formed on the inner circumferential surface of the groove. After the raising of the lens barrel to put the plate claws into the groove of the apparatus body through the cutout regions respectively, the lens barrel is turned so that the plate claws move to deeper positions inside the groove. In this way, the lens barrel is attached to the apparatus body. When the lens barrel is turned, each of the inner circumferential convex parts that are formed on the inner circumferential surface of the groove is fitted into the concave part that is formed in the outside of the plate claw, thereby determining the position of the lens barrel around the optical axis.
However, the related-art optical apparatus that is disclosed in Japanese Unexamined Patent Application Publication No. H4-307528 has a disadvantage in that the shape of the lens barrel is inevitably complex because it is necessary to form the concave part in the plate claw for position determination, which results in increased production cost. As another disadvantage, since the cutout regions are formed at the apparatus-body side, a person who attaches the lens barrel to the apparatus body has to, for example, bend the upper part of the body for looking up the apparatus body from a lowered eye level to confirm the positions of the cutout regions. For this reason, the efficiency of lens barrel attachment is low.